The American Thunder 40 Series is the most aggressive sounding street and strip muffler in Flowmaster's product line. The 40 Series will generate extreme interior resonance within the vehicle. If you want to really hear your exhaust system inside as well as outside your vehicle the 40 Series is for you. These mufflers take the sound waves produced in the exhaust, and cancel them against angled baffles built into the muffler case. This improves both horsepower and fuel economy.

The Flowmaster 40 Series two chamber muffler is the original bad boy for street/strip cars. Made of 16 gauge, aluminized steel, the unique design cancels out noise, but makes big power.

This is the muffler you have been waiting for. The Flowmaster crew has been developing this muffler over the last two years to provide the best sound while retaining maximum performance. The body measures 4" x 9-1/2" x 13" long so it can fit up under your car.